1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a washing method in a steam injection type washing machine in which steam is injected into a wash tub at the top of the wash tub.
2. Description of the Related Art
Referring to FIG. 1, a conventional washing machine is illustrated. As shown in FIG. 1, the conventional washing machine includes a cabinet 2 defining the appearance of the washing machine, and carrying a door 1. The conventional washing machine also includes a wash tub including a tub 4 fixedly installed in the cabinet 2, and a drum 6 rotatably installed in the tub 4, and provided with a plurality of water holes 5. The conventional washing machine further includes a drive unit 8 connected with the drum 6 via a rotating shaft 7, and adapted to rotate the drum 6, a water supply unit 10 for supplying wash water into the wash tub, and a drainage unit 12 for draining wash water from the wash tub.
A detergent supply unit 14 containing detergent therein is arranged at a top portion of the cabinet 2. The water supply unit 10 is connected with the detergent supply unit 14 so that detergent can be supplied from the detergent supply unit 14 into the wash tub, along with wash water.
The tub 4 is connected, at the top thereof, to the top of the cabinet 2 via a spring 16 while being connected, at the bottom thereof, to the bottom of the cabinet 2 via a damper 17 having a damping function.
The above mentioned washing machine may further include a heater 20 adapted to heat wash water supplied into the wash tub. The tub 4 is recessed at a bottom portion thereof to provide a heater chamber 21 for receiving the heater 20 therein.
Now, operation of the conventional washing machine having the above mentioned configuration will be described.
When a wash cycle is begun, wash water is supplied into the tub 4 and drum 6 in accordance with the amount of clothes contained in the drum 6, along with detergent. In this state, the drum 6 is rotated in accordance with a drive force from the driving unit 8. As a result, a washing operation is carried out by virtue of a combination of an emulsification function of the detergent with frictional forces generated between the drum 6 and water flows in the drum 6.
When the heater 20 operates during the washing operation in accordance with an operating mode set by the user, the wash water supplied into the tub 4 and drum 6 is heated. That is, an increase in wash temperature is achieved, so that it is possible to easily remove stains from clothes.
After completion of the wash cycle, the wash water is drained. Fresh wash water is then again supplied into the tub 4 and drum 6. Simultaneously, the drum 6 is rotated to execute a rinse cycle. Finally, the drum 6 is rotated at high speed to execute a spin-dry cycle. Thus, the clothes are completely washed.
In the above mentioned conventional washing machine, wash water is supplied into the tub 4 and drum 6 through top portions thereof, and then permeates into clothes contained in the drum 6 to wet the clothes. On the other hand, the heater 20 is arranged at the bottom of the tub 4. For this reason, in a washing mode using wash water heated by the heater 20, the clothes contained in the drum 6 are wetted by cold wash water at an initial water supply stage without being wetted by hot wash water. As a result, the wetting speed of the clothes is low, so that the efficiency of the heater 20 is degraded.
In the conventional washing machine, the heater chamber 21 should be provided at the tub 4 in the form of a separate space to install the heater 20. In particular, the heater chamber 21 is provided by downwardly recessing a bottom portion of the tub 4. Due to such a structure, wash water supplied into the tub 4 unnecessarily fills the heater chamber 21, so that there is waste of wash water. Furthermore, detergent is also left in the heater chamber 21, so that there is waste of detergent.